Toshi,
Don't misunderstand me, I have, in my paint drawer, Tamiya, ModelMaster, Vallejo Air (WWII German), LifeColor, PolyScale, and a few others. My preference, assuming no other brand is significantly more accurate for the model I'm building, is always Tamiya. However I'll use what my research has told me works best - in acrylics.
As to airbrushes...... I started with a set of 3 Chinese made A/B's. Two of them broke after my having used them less than twice each. I keep the third one buried in my A/B drawer. My go to A/B for the last three years has been Badger's 105 Patriot. I also have the Badger 155 Anthem for covering large areas. Both are very good A/B's as far as I'm concerned. One of my Christmas presents to myself is an Iwata HP-C Plus. I haven't tried it yet but I'm planning on using it on my next kit which I've finally decided is not going to be the Corsair (HobbyBoss 1/48) that I was thinking about but, instead, the 1/48 Tamiya Fock Wulf 190 F-8. I figure it'll give me some practice in painting German WWII camo as well as going together relatively easily - I hope.
Mike
P.S. I think once one has a decent A/B that he/she has used and with which one has become familiar as well as competant/skillfull the only reason to move to any other A/B would be out of sheer curiousity (I'm guilty)